Actix Web

[dependencies]
dynamic-config-actix = "<version>"

The same two pieces through Actix's seams: DynamicConfig is a Transform middleware, Config<T> a FromRequest extractor.

App::new()
    .wrap(DynamicConfig::new(sections![Server, Features]))
    .service(handler);

Where Actix differs from axum

• wrap order reads outside-in — the last wrap runs first. The snapshot middleware can sit anywhere; it only needs to run before the handler.
• Extensions live behind a RefCell, so the free function snapshot(&HttpRequest) answers a clone of the snapshot rather than a reference — cheap (it is a map of Arcs), and the reason its signature differs from axum's.
• Scoped services nest exactly as axum's routers do: an outer wrap and a web::scope(...).wrap(...) merge, inner wins per type.
• The rejection type implements ResponseError; the body a client sees is generic on purpose, and the type path stays in Display for logs.

Workers each run their own copy of the app factory; the sections list is behind an Arc, so N workers share one list and each request anywhere takes its own snapshot.

Tests: dynamic-config-actix/tests/scope.rs — kept parallel to the axum file, case for case; actix_two_sections is the runnable example.